Stroke is the 5th leading cause of death in the US, with one person dying every 4 minutes as a result. For black people, stroke is the 3rd leading cause of death.
Approximately 800,000 people have a stroke each year; about one every 40 seconds. Only heart disease, cancer, chronic lower respiratory diseases and accidents are more deadly.1-3
Strokes occur due to problems with the blood supply to the brain: either the blood supply is blocked or a blood vessel within the brain ruptures, causing brain tissue to die. A stroke is a medical emergency, and treatment must be sought as quickly as possible.
There are three main kinds of stroke:
- Ischemic strokes
- Hemorrhagic strokes
- Transient ischemic attacks(TIAs), also referred to as mini-strokes
What is stroke?4
Stroke occurs when the supply of blood to the brain is either interrupted or reduced. When this happens, the brain does not get enough oxygen or nutrients which causes brain cells to die.
Strokes occur due to problems with the blood supply to the brain; either the blood supply is blocked or a blood vessel within the brain ruptures.
There are three main kinds of stroke; ischemic, hemorrhagic and TIA. This article will focus on ischemic and hemorrhagic strokes, as there is a separate Knowledge Center article for TIAs, which goes into specific detail about them.
In the US, approximately 40% of stroke deaths are in males, with 60% in females. According to the American Heart Association (AHA), compared to white people, black people have nearly twice the risk of a first-ever stroke and a much higher death rate from stroke.3
In 2009, stroke was listed as the underlying cause of death in 128,842 persons in the US, resulting in an age-adjusted rate of 38.9 deaths per 100,000 population. The rate was almost twice as high among non-Hispanic blacks (73.6 per 100,000), and the rate of premature death from stroke was also higher among non-Hispanic blacks than their white counterparts (25.0 versus 10.2).17
Stroke is also more likely to affect people if they are overweight, aged 55 or older, have a personal or family history of stroke, do not exercise much, drink heavily, smoke or use illicit drugs.5
What causes stroke?
The different forms of stroke have different specific causes.
Ischemic stroke4
Ischemic stroke is the most common form of stroke, accounting for around 85% of strokes. This type of stroke is caused by blockages or narrowing of the arteries that provide blood to the brain, resulting in ischemia – severely reduced blood flow.
These blockages are often caused by blood clots, which can form either in the arteries connecting to the brain, or in other blood vessels before being swept through the bloodstream and into narrower arteries within the brain. Clots can be caused by fatty deposits within the arteries called plaque.
Hypertension can lead to rupturing of blood vessels and hemorrhagic stroke.
Hemorrhagic stroke4,6
Hemorrhagic stroke are caused by arteries in the brain either leaking blood or bursting open. The leaked blood puts pressure on brain cells and damages them. Blood vessels can burst or spill blood in the middle of the brain or near the surface of the brain, sending blood into the space between the brain and the skull.
The ruptures can be caused by conditions such as hypertension, trauma, blood-thinning medications and aneurysms (weaknesses in blood vessel walls).
Intracerebral hemorrhage is the most common type of hemorrhagic stroke and occurs when brain tissue is flooded with blood after an artery in the brain bursts. Subarachnoid hemorrhage is the second type of hemorrhagic stroke and is less common. In this type of stroke, bleeding occurs in the subarachnoid space – the area between the brain and the thin tissues that cover it.
Transient ischemic attack (TIA)4,6
TIAs are different from the aforementioned kinds of stroke because the flow of blood to the brain is only briefly interrupted. TIAs are similar to ischemic strokes in that they are often caused by blood clots or other debris.
TIAs should be regarded as medical emergencies just like the other kinds of stroke, even if the blockage of the artery is temporary. They serve as warning signs for future strokes and indicate that there is a partially blocked artery or clot source in the heart.
According to the Centers for Disease Control and Prevention (CDC), over a third of people who experience a TIA go on to have a major stroke within a year if they have not received any treatment. Between 10-15% will have a major stroke within 3 months of a TIA.6
Recent developments on stroke causes from MNT news
Poor thinking skills linked to greater risk of heart attack, stroke
Individuals with poor executive function – a set of thinking skills related to planning, problem-solving and reasoning – may be at greater risk of heart attack and stroke, according to a new study published in the journal Neurology.
Longer working hours linked to greater stroke risk
Workaholics may be jeopardizing their health after a new study reveals working 55 hours or more per week may lead to 33% greater risk of stroke.
Stroke risk for older men who take alpha-blockers
Alpha-blockers are used to treat a variety of conditions, including high blood pressure, Raynaud’s disease and to improve urine flow in older men with enlarged prostates. Now, a new study suggests there is a higher risk of ischemic stroke for men who take alpha-blockers but who are not already taking other blood pressure medications.
Broken sleep raises risk of stroke
Elderly people who sleep poorly and awaken frequently are more likely to have hardened blood vessels or oxygen-starved tissue in the brain, according to a report published in the journal Stroke.
Symptoms of stroke7-9
Strokes occur quickly and, as such, symptoms of stroke often appear suddenly without warning.
The main symptoms of stroke are as follows:
- Confusion, including trouble with speaking and understanding
- Headache, possibly with altered consciousness or vomiting
- Numbness of the face, arm or leg, particularly on one side of the body
- Trouble with seeing, in one or both eyes
- Trouble with walking, including dizziness and lack of co-ordination.
Strokes can lead to long-term problems. Depending on how quickly it is diagnosed and treated, the patient can experience temporary or permanent disabilities in the aftermath of a stroke. In addition to the persistence of the problems listed above, patients may also experience the following:
- Bladder or bowel control problems
- Depression
- Pain in the hands and feet that gets worse with movement and temperature changes
- Paralysis or weakness on one or both sides of the body
- Trouble controlling or expressing emotions.
How to diagnose a stroke7,8,10
Strokes happen fast and will often occur before an individual can be seen by a doctor for a proper diagnosis.
The acronym F.A.S.T. is a way to remember the signs of stroke, and can help identify the onset of stroke more quickly:
- Face drooping: if the person tries to smile does one side of the face droop?
- Arm weakness: if the person tries to raise both their arms does one arm drift downward?
- Speech difficulty: if the person tries to repeat a simple phrase is their speech slurred or strange?
- Time to call 911: if any of these signs are observed, contact the emergency services.
The faster a person with suspected stroke receives medical attention, the better their prognosis and the less likely they will be to experience lasting damage or death.
In order for a stroke patient to get the best diagnosis and treatment possible, they will need to be treated at a hospital within 3 hours of their symptoms first appearing.
Both ischemic strokes and hemorrhagic strokes require different kinds of treatment. Unfortunately, it is only possible to be sure of what type of stroke someone has had by giving them a brain scan in a hospital environment.
There are several different types of diagnostic tests that doctors can use in order to determine which type of stroke has occurred:11
CT scans of the brain are one of few ways to determine which type of stroke a person has had.
- Physical examination: a doctor will ask about the patient’s symptoms and medical history. They may check blood pressure, listen to the carotid arteries in the neck and examine the blood vessels at the back of the eyes, all to check for indications of clotting
- Blood tests: a doctor may perform blood tests in order to find out how quickly the patient’s blood clots, the levels of particular substances (including clotting factors) in the blood, and whether or not the patient has an infection
- CT scan: a series of X-rays that can show hemorrhages, strokes, tumors and other conditions within the brain
- MRIscan: radio waves and magnets create an image of the brain to detect damaged brain tissue
- Carotid ultrasound: an ultrasoundscan to check the blood flow of the carotid arteries and to see if there is any plaque present
- Cerebral angiogram: dyes are injected into the brain’s blood vessels to make them visible under X-ray, in order to give a detailed view of the brain and neck arteries
- Echocardiogram: a detailed image of the heart is created to check for any sources of clots that could have traveled to the brain to cause a stroke.
Recent developments on stroke diagnosis from MNT news
Risk of stroke may be predicted by grip strength
A large international study has associated weak grip strength with increased risk of heart attack and stroke, as well as increased risk of death from both cardiovascular and non-cardiovascular diseases.
‘Strokefinder’ helmet makes rapid stroke diagnoses
A helmet that uses microwaves to examine brain tissue has been found to accurately diagnose the type of stroke that a patient has suffered. If developed, the device could lead to early and correct diagnosis of stroke and may improve treatment for what is currently the 5th highest cause of death in the US.
New smartphone apps ‘detect epilepsy and improve stroke care’
In these modern times, there is practically a smartphone app for all aspects of life. Now, new research has detailed two new apps that could help people detect epileptic seizures and receive better treatment for stroke.
Research scheduled for publication in the July 2016 issue of the journal Neurophotonics reveals proof of principle for the use of frequency-domain near-infrared spectroscopy (fdNIRS) to study brain oxygenation in the first few hours of stroke onset.
The researchers used the OxiplexTS(®) fdNIRS system to assess oxygen levels in the brains of cadavers, patients after a stroke and in healthy people and while the use of this technology is in a preliminary stage, it appears to hold promise for early detection and monitoring of stroke.18
Treatments for stroke
As the two main different kinds of stroke, ischemic and hemorrhagic, are caused by different factors, both require different forms of treatment. It is not only important that the type of stroke is diagnosed quickly to reduce the damage done to the brain, but also because treatment suitable for one kind of stroke can be harmful to someone who has had a different kind.
Ischemic stroke
Ischemic strokes are caused by arteries being blocked or narrowed and so treatment focuses on restoring an adequate flow of blood to the brain.
Treatment can begin with drugs to break down clots and prevent further ones from forming. Aspirin can be given, as can an injection of a tissue plasminogen activator (TPA). TPA is very effective at dissolving clots but needs to be injected within 4.5 hours of stroke symptoms manifesting themselves.
Surgeons are able to remove plaque and any other obstructions from the carotid artery through surgery.
Emergency procedures include administering TPA via catheter directly into an artery in the brain or using a catheter to physically remove the clot from its obstructive position. Recent studies have cast doubt as to the effectiveness of these methods, and so research is still ongoing as to how beneficial these procedures are.
There are other procedures that can be carried out to decrease the risk of future strokes or TIAs. A carotid endarterectomy involves a surgeon opening the carotid artery and removing any plaque that might be blocking it.
Alternatively, an angioplasty involves a surgeon inflating a small balloon in a narrowed artery via catheter and then inserting a stent (a mesh tube) into the opening in order to prevent the artery from narrowing again.
Hemorrhagic stroke
Hemorrhagic strokes are caused by bleeding into the brain and so treatment focuses on controlling the bleeding and reducing the pressure on the brain that it is causing.
Treatment can begin with drugs being given to reduce the pressure in the brain, overall blood pressure, prevent seizures and prevent sudden constrictions of blood vessels. If the patient is taking anti-coagulant or anti-platelet medication like Warfarin or Clopidogrel, they can be given drugs or blood transfusions to counter the medication’s effects.
Surgery can be used to repair any problems with blood vessels that have led or could lead to hemorrhagic strokes. Surgeons can place small clamps at the base of aneurysms or fill them with detachable coils to stop blood flow to them and prevent rupture.
Surgery can also be used to remove small arteriovenous malformations (AVMs) if they are not too big and not too deep within the brain. AVMs are tangled connections between arteries and veins that are weaker and burst more easily than other normal blood vessels.14
Rehabilitation13,15
Strokes are life-changing events that can affect a person both physically and emotionally, temporarily or permanently. After a stroke, successful recovery will often involve specific rehabilitative activities such as:
- Speech therapy – to help with problems producing or understanding speech. Practice, relaxation and changing communication style, using gestures or different tones for example, all help
- Physical therapy– to help a person relearn movement and co-ordination. It is important to get out and about, even if it is difficult at first
- Occupational therapy – to help a person to improve their ability to carry out routine daily activities, such as bathing, cooking, dressing, eating, reading and writing
- Joining a support group – to help with common mental healthproblems such as depression that can occur after a stroke. Many find it useful to share common experiences and exchange information
- Support from friends and family – to provide practical support and comfort. Letting friends and family know what can be done to help is very important.
